On Nov. 7, 2017, President Moon Jae-in greeted visiting U.S. President Donald Trump at Camp Humphreys in Pyeongtaek, a U.S. military base some 75 km south of Seoul.Few had known about Moon's welcoming plan for Trump until the last minute. Why did the South Korean leader brave the controversy about excessive modesty by choosing the unusual, abrupt protocol?President Moon wanted to highlight the new massive U.S. military facility as the symbol of the strong ROK-U.S. alliance ― and that Seoul shouldered 92 percent of the total construction cost of $10.7 billion.In a joint news conference, however, President Trump said, "In fact, we also paid part of the cost for this base. And it was to protect South Korea, not America." The real estate developer-turned-president then said, as if in jest, "Had I undertaken it, I would have done so at a far lower cost."Trump was not joking at all, as it turned out later.Last year, South Korean and U.S. officials held 10 rounds of talks over how to share the upkeep costs for U.S. troops stationed here but failed to strike a deal. The working group officials narrowed their differences to 100 billion won ($89.52 million) or so, but the progress fell through because the "U.S. leadership opposed the idea," Yonhap News Agency reported on Dec. 25. President Trump reportedly called for doubling Seoul's share from this year's 960 billion won, and U.S. negotiators demanded a 50 percent rise to $1.2 billion (or 1.36 trillion won), larger than the total increase of the past 13 years.The gap is so wide that the two sides have not even decided yet on a future negotiation schedule. Washington also proposed to hold the defense cost-sharing talks every year instead of every five years as is the case now. It was a thinly veiled move to raise South Korea's share more steeply, which Seoul rejected.The two governments were supposed to conclude the talks by the end of 2018. If they fail to reach an agreement by March, the U.S. Forces Korea says it will have to put 8,700 Korean workers on unpaid leave from April. Since his campaign days, President Trump has complained about some U.S. allies which he claimed try to defend their country at America's expense. Trump included South Korea in the "free riders." Coincidentally or not, Trump reiterated his position that U.S. allies should shoulder a heavier burden, after the aborted bargaining with Seoul. On Dec. 24, he wrote on Twitter, "We are substantially subsidizing the Militaries of many VERY rich countries all over the world, while at the same time these countries take total advantage of the U.S. and our TAXPAYERS." Trump seems to have upcoming cost-sharing talks with Japan and NATO in mind in demanding as many concessions from Seoul as possible. Analysts say Washington may go as far as to threaten the reduction of the 28,500 troops stationed here if Seoul refuses to accept its demand. The U.S. leader reportedly does not want his country to continue its role as a global police force. Trump's reasoning seems to be that if America has to keep playing that role, the beneficiaries should pay the expenses ― and the larger the share, the better. Aside from whether the world needs the U.S. to act as a police force and whether America is doing its role properly, Washington's demand on Seoul goes too far in many ways. South Koreans with a minimal sense of sovereignty have complained about the unequal alliance between Seoul and Washington. Nothing shows this inequality better than the sharing of defense costs between the two countries. South Korea, Japan and Germany are virtually the only countries that share the costs of stationing U.S. troops in their land by signing a "special measures agreement (SMA)." Germany's contribution is nominal by accounting for 0.001 percent of its GDP. Japan's payment is larger than South Korea's, but Seoul pays 0.1 percent of its GDP, higher than Tokyo's 0.08 percent. Given there are 60,000 U.S. troops in Japan, South Korea's payment nearly doubles that of Japan's, with about 190 million won per American soldier a year. As seen in the Camp Humphreys case, South Korea funded almost all of the relocation expenses of the U.S. forces. Add to these the several trillion won required to decontaminate and restore the former U.S. base in Yongsan, then Seoul's financial burden becomes astronomical, let alone the controversy over "environmental sovereignty." Ostensibly South Korea is known to pay half of the maintenance costs ― labor cost for Korean personnel working for the USFK, construction expenses within bases and logistics support costs. Considering various indirect support, however, Seoul is paying 60 percent to 70 percent of the total cost.So much so the USFK has not been able to spend the yearly contribution, and the unspent amount accumulated to more than 1 trillion won in the late 2000s. There remained about 330 billion won in unused money as of the end of 2016. The USFK deposited the money at a "community bank," which in turn kept it at the Bank of America. Faced with the criticism that the U.S. military practiced usury using Korean taxpayers' money, the U.S. Department of Defense made a lame excuse, saying, "The interest income did not go into the USFK, and was used to run the community bank. So, please forget about it." It was no surprise civic groups raised an issue with the U.S. military infringing on its host country's "fiscal sovereignty." The Moon Jae-in administration should squarely cope with unreasonable U.S. demands in future negotiations. South Korean officials ought to emphasize the defense cost-sharing itself is not obligatory according to the Status of Forces Agreement (SOFA), Seoul is already paying too large a sum, and the U.S. troops here are not just to defend South Korea, and increasingly so at a time of inter-Korean rapprochement.Alliance accompanies price, which should be balanced and reasonable. The Trump administration should admit the excessiveness of its demands, realizing America cannot decide the regional order by forcing its allies to shoulder most of the expenses. Or, many South Koreans will be asking, "If police officers are like this, who needs villains?" The 70-year-long alliance faces another major test this year.

Choi Sung-jin is a Korea Times columnist. Contact him at choisj1955@naver.com.